1. Field of the Invention
One embodiment of the disclosed invention relates to a semiconductor device and a display device including the semiconductor device.
2. Description of the Related Art
Attention has been focused on a technique for forming a transistor (also referred to as thin film transistor (TFT)) using a semiconductor thin film formed over a substrate having an insulating surface. The transistor is applied to a wide range of electronic devices such as an integrated circuit (IC) and an image display device (display device).
A technique for forming a pixel portion and a driver circuit portion using transistors over the same substrate in a display device has been actively developed.
A silicon-based semiconductor material is widely known as a material for a semiconductor thin film applicable to a transistor. As another material for a semiconductor thin film, an oxide semiconductor material has been attracting attention.
For example, a transistor whose active layer includes an amorphous oxide containing indium (In), gallium (Ga), and zinc (Zn) and having an electron carrier concentration lower than 1018/cm3 is disclosed (see Patent Document 1).